#define _CRT_SECURE_NO_WARNINGS  1
#include <stdio.h>
int  febo(int x)
{
	if (x>2)
		return febo(x - 2) + febo(x - 1);
	else
		return 1;
}
int main()
{
	int n = 0;
	int m;
	scanf("%d", &n);
    m=febo(n);
	printf("%d\n", m);
	return 0;
}